State police still don't know why a Manlius man drove his motorcycle into oncoming traffic Saturday on state Route 481 in Volney.

Stephen J. Cain, 58, and his passenger, Patricia Sherwood, 52, were killed on their way back from Harborfest when his southbound Harley-Davidson crashed head-on into a Chevrolet Tahoe sport utility vehicle.

State police have said the motorcycle was in the wrong lane for some time before the crash, but investigators couldn't pinpoint why.

An autopsy showed Cain and Sherwood suffered multiple traumatic injuries. But it did not reveal any medical conditions that might explain why the motorcycle entered the northbound lane, state police Investigator Eric Costello said. The autopsy also showed Cain was not intoxicated when the crash happened, Costello said.